The strings of a stringed musical instrument are provided on the frame of the instrument all under fairly high tension. If the instrument is allowed to stand with the strings held tensioned, various objections could result. For example, the strings would be elongated or broken due to fatigue, or the members holding the strings under tension would be deformed or damaged. Accordingly it is desirable to loosen all the strings after playing, but if loosened, the strings must be tensioned and tuned one by one with use of a pitch pipe or the like before playing the instrument. The tuning procedure requires much labor and is very cumbersome especially for beginners.